The Istanbul Public Prosecutor’s Office Wednesday prepared a civil lawsuit against 20 suspects involved in the killing of Saudi journalist Jamal Khashoggi.

In a statement, Istanbul Chief Public Prosecutor İrfan Fidan said the investigation into the Saudi journalist’s murder has concluded.

The statement noted that the indictment accuses former deputy head of Saudi Arabia’s general intelligence, Ahmed al-Asiri, and former royal court adviser Saud al-Qahtani as having “instigated premeditated murder with monstrous intent.”

It accuses 18 others of carrying out the killing of Khashoggi, a U.S. resident and columnist for The Washington Post, the prosecutor’s office said in a statement.

The indictment was based on analysis of mobile phone records of the suspects, records of their entry and exit to Turkey and their presence at the consulate, witness statements and analysis of Khashoggi’s phone, laptop and iPad, the statement said.

Khashoggi was killed and dismembered by a group of Saudi operatives in the country’s consulate in Istanbul on Oct. 2, 2018. Initially denying and later downplaying the incident as an accidental killing in a fistfight, Riyadh finally admitted almost three weeks after the disappearance that Khashoggi was murdered in a premeditated fashion but denied any involvement of the royal family.

The incident was blamed on lower-level officials, including five who are now facing the death penalty over their involvement. A Saudi public prosecutor said in late March that they would seek the death penalty for five suspects among the 21 involved in the case. Ankara has said the statement is not satisfactory and demanded genuine cooperation from Riyadh.

To this day, Khashoggi’s body has not been recovered, and the kingdom has remained silent on its whereabouts.